Canada or "the Canadas" as it was also known at the time, was composed mostly of the territories of New France (Quebec, Acadia) that Britain had won from France during the Seven Years War, or French and Indian War as it's called in the US. (France had ceded Louisiana to Spain just before the war ended.)

In 1763, Britain found itself as masters of some 70-80,000 French Catholic colonists, essentially abandoned by France at the peace negotiations. What to do with them would ultimately set the tone of Britain's relations with the Thirteen Colonies and help to trigger the American Revolution.

James Murray, military governor of Quebec from 1760-63 and civil governor after 1763, was faced with a potentially hostile population in Quebec, and increasing pressure from New England merchants who had wanted to reap the rewards of conquest, enforce their "rights as Englishmen" and sideline the French colonists and their Catholic faith. Sectarianism was prevalent then and New England opposed any efforts to give the "papist" faith any accommodation. The Quebecois didn't like their British rulers -- but they trusted the New Englanders even less.

Murray, and his successor Guy Carleton, opted to placate the local Quebecois with generous accommodations for their property, language, civil law and religion -- mostly out of fear that a heavy hand might encourage them to rebel. Also, they found common ground with Quebec's political and clerical elites and didn't like the New England merchants' demands and behaviour.

The 1774 Quebec Act enshrined these accommodations into British law, enraging the Thirteen Colonies. The act became one of the Intolerable Acts that compelled them to revolt against the Crown. It did enough to ensure that Quebec would stay true to the Crown, but not enough to encourage them to take up arms for England. In Quebec, there was no upside to siding with one or the other, as choosing a side might cost them their liberties under Britain, or cultural assimilation under America. They preferred to let les Anglais and les Bostonnais fight among themselves.

The city of Quebec, the seat of British political and military power in North America, was the most formidable walled fortress on the continent (which Benedict Arnold would soon discover when he tried to attack it in 1775, without any heavy artillery). Both Quebec and the naval port at Halifax, the North American station for the Royal Navy, would serve as bases from which Britain would plan, organize and launch their campaigns throughout the American Revolution. Control of the Hudson Valley, a critical route to both Canada and America, was a strategic goal for both sides.

Canada, as the nearest British colony, was heavily enmeshed in British efforts during the revolution, and a target of US Continental Army attacks and frequent privateering coastal raids.